Cells stick to dish in Embryoid Bodies

I have been culture mouse ES cells and use them to form EBs in suspension. They have been working for almost a year and recently it has stopped. The ES cells that are plated in the petri dishes are actually adhering to the dish. I am trying to troubleshoot this problem. This has caused a stand still in my research and i need to resolve this problem. Does anyone have any suggestions? I am going to try the hanging drop method to see if this works.

Make sure you are using non-coated bacterial dishes and not tissue culture treated dishes. If this isn't the problem, I'd say there may be a problem with your cells. The cells can start acting weird if they are in a very late passage, so if your cells are too old you may want to try an earlier passage. Your cells may also be differentiated due to improper care or passaging in which case you may also want to try another set of cells. Good luck!